Minarets are constructed in a wide variety of forms ranging from thick, squat spiral ramps, as at Samarra, Iraq (built 848–852), to soaring, delicate, pencil-thin spires. Often the minaret is square at the base, where it is attached to the mosque. Above this square base it may rise in a series of circular, hexagonal, or octagonal stages, each marked by a projecting balcony. At the top is a bulbous dome, an open pavilion, or a metal-covered cone. The upper parts of the minaret are usually richly decorated with carving. The steps may be internal or external. The number of minarets per mosque also varies, from one to as many as six. These towers were built to be “landmarks of Islām”—to be visible from afar and to stamp a site with Islāmic character.